sedimentary
Conglomerate (River Rock Aggregate)
Conglomerate (Lithic-clast conglomerate)
Hardness: Variable (6-7 for quartz clasts); Color: Multicolored (brown, grey, reddish, black); Luster: Dull to earthy; Structure: Clastic, consisting of rounded to sub-angular pebbles embedded in a fine-grained matrix/cement; Cleavage: None.
- Hardness
- Variable (6-7 for quartz clasts)
- Color
- Multicolored (brown, grey, reddish, black)
- Luster
- Dull to earthy
Identified More sedimentary →
Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Hardness: Variable (6-7 for quartz clasts); Color: Multicolored (brown, grey, reddish, black); Luster: Dull to earthy; Structure: Clastic, consisting of rounded to sub-angular pebbles embedded in a fine-grained matrix/cement; Cleavage: None.
Formation & geological history
Formed by the accumulation and subsequent lithification of rounded water-worn rock fragments. These are typically deposited in high-energy environments like riverbeds, alluvial fans, or beaches. The age can range from Recent to billions of years old.
Uses & applications
Used primarily in the construction industry as decorative aggregate, building stone (as seen in the mural/wall in the image), and as road base material. Occasionally used as an architectural veneer.
Geological facts
Conglomerate is often called a 'puddingstone' because it looks like a pudding filled with raisins and nuts. Famous examples include the Roxbury Conglomerate in Massachusetts. It is technically more of a 'rock type' than a single mineral.
Field identification & locations
Identify in the field by looking for rounded pebbles (clasts) larger than 2mm that are clearly cemented together by a finer material. Found globally in ancient riverbeds or mountain-front deposits. For collectors, look for unique colors or jasper-rich clasts.
More like this
Other sedimentary specimens
Sandstone or Siltstone
Arenite (if sandstone)
Sedimentary
Sandstone
Arenite (primarily SiO2)
sedimentary
Shale or Slaty Mudstone
Argillaceous sedimentary rock
sedimentary
Chert Breccia
Brecciated Chert (Microcrystalline Silica)
sedimentary
Sandstone (Quartz-rich)
Arenite (SiO2)
sedimentary
Sandstone (with man-made markings)
Arenite (composed primarily of Quartz, SiO2)
sedimentary